To better ensure privacy, Android P restricts access to mic, camera, and all SensorManager sensors from apps that are idle. While your app's UID is idle, the mic reports empty audio and sensors stop reporting events. Cameras used by your app are disconnected and will generate an error if the app tries to use them. In most cases, these restrictions should not introduce new issues for existing apps, but we recommend removing these requests from your apps.

This is a very good move, and I doubt anyone will have any objections.

In line with these changes, Android P will warn users with a dialog when they install an app that targets a platform earlier than Android 4.2 (targetSdkVersion less than 17), and future platform versions will continue to increment that lower bound.

Expect scary warning dialogs when installing older applications. This should encourage developers to update their applications as users complain in the review sections of the Play Store. Hopefully.

You can now access streams simultaneously from two or more physical cameras on devices running Android P. On devices with either dual-front or dual-back cameras, you can create innovative features not possible with just a single camera, such as seamless zoom, bokeh, and stereo vision. The API also lets you call a logical or fused camera stream that automatically switches between two or more cameras.

Definitely neat.

There's a lot more stuff in this preview release, and more features will certainly follow over the coming months.